Fig. 6

SPARC and TNF-α regulate hCMEC/D3 tight junction protein expression. a Confluent hCMEC/D3 cultures treated with SPARC (0.1, 1, 10 μg/ml) or TNF-α (200 U/ml) for 24 h were analyzed for tight junction (TJ) expression. TJ expression was quantified by immunoblot analysis of hCMEC/D3 lysates with the TJ-negative human astrocytoma cell line (Astro) ccf-sttg1 (Sigma) lysate as a negative control. A reduction in endothelial TJ expression was observed with increasing SPARC exposure above 1 μg/ml. b Increasing exogenous SPARC from 0.1 to 1 μg/ml lowered both ZO-1 (by 23 %) and occludin (by 20 %) expression. The bars represent the mean expression from 5 (ZO-1) and 4 (occludin) experiments, and error bars represent the SEM. **P < 0.001; ***P < 0.0001 by ANOVA and Student-Newman-Keuls multiple comparisons test